1. Field of the Invention
The invention relates to gas cooking ranges and, more particularly, to a gas cooking range having improved characteristics of heat circulation, gas discharge, compactness, and, in general, energy efficiency.
2. Description of the Prior Art
Gas cooking ranges have been known for many years and have been provided with a number of features to increase the convenience of cooking foods of various types. Most prior gas ranges constitute a box-type structure with at least one front opening, the other three sides and the bottom and top forming a substantially unitary structure. The front opening typically is provided with at least one oven door and at least one broiler door. A single oven burner usually is provided, with the burner being located at the bottom of the oven compartment and also serving to provide heat for the broiler compartment. A single control knob usually regulates the burner for full power operation for a broiling operation or various lower temperature settings for baking operations in the oven. The air provided for combustion is generally supplied from the bottom of the oven through a number of openings and the products of combustion are vented from the back of the oven, finally discharging into the room in which the oven is contained by being vented through an opening provided near the upper, rear portion of the range. The top of the range typically is provided with a set of four burners, each having its own gas control valve. By this construction, the top burners can be activated in any sequence at any time. Although various other features such as clocks, timers, backguard lights, and so forth can be provided, the basic features of an oven, broiler compartment, and range top burners are common to most gas ranges.
Prior gas ranges, although effective to cook foods in a desired manner, are not entirely satisfactory from an energy efficiency viewpoint. Modifications such as increased insulation and improved door seals have been made in some cases, but practical results have not been very great. The range top burners have a heating efficiency of approximately 45-50%, a very low figure. Oven efficiencies tend to be exceedingly low, on the order of only 5-7%, because of an industry requirement that the average broiler temperature for an enclosed broiler shall reach 530 degrees Fahrenheit above room temperature within 12 minutes and shall reach 530 degrees Fahrenheit above room temperature within 16 minutes for broilers which are heated by oven burners using separate burners located in the oven compartment. In short, a tremendous amount of heat is liberated with a short period of time and the excess heat has no place to go except to heat the inside sheet metal structure, oven racks, and food which may be placed inside the oven, the rest of the heat being inefficiently exhausted through a flue vent.
An industry standard for the temperature of combusting gases at the mouth of the flue vent is a maximum of 480 degrees Fahrenheit above room temperature. This is quite close to the 530 degrees Fahrenheit broiler compartment maximum temperature. Whether the range is used for low temperature oven cooking or high temperature broiling, the inside oven temperature and flue vent temperature are practically the same. In turn, the useful work done by the large oven compartment in terms of heat input and heat output is very, very small. It is inefficient to heat the inside of the oven compartment and not be able to use the high temperature flue vent heat for any useful purpose.
As mentioned previously, certain minor modifications have been made in an attempt to improve the efficiency of gas cooking ranges. These modifications have not been effective and fall far short of the changes needed to effectively utilize available energy. Certain problem areas, such as the inefficiency of the range top burners and the inefficiency of the oven design, have been mentioned already. Other problems which have not been addressed relate to ignition of various burners included as part of the range. So-called pilotless ignition systems have been developed, but although these systems are energy efficient, they lead to corrosion of metal components of the range due to condensation of water on the metal surfaces. Piloted ignition systems small enough to barely drive away moisture have not been effective enough at igniting the burners when desired. A desirable ignition system would provide a small flame just large enough to avoid moisture condensation and, at the same time, would be able to effectively ignite the various burners included with the range.
Another problem not adequately addressed by prior ranges relates to baking small quantities of food. Even if only a small quantity of food needs to be cooked, the entire oven/broiler compartment needs to be heated, an obvious waste of energy. Desirably, a small oven compartment would be provided which would be very energy efficient in the sense that only a small compartment would need to be heated in order to cook a small quantity of food.
Yet another problem which has not been adequately addressed relates to the removal of liquids extracted from food during the cooking process. Prior ranges employ a drip pan which, during the cooking process, becomes heated. When grease or other liquids drip onto the heated pan, smoke and odors are produced which eventually are discharged from the flue vent. A difficult-to-clean film is deposited on surrounding portions of the range. Desirably an improved drip pan system would be provided such that the discharge of smoke and undesirable odors is greatly minimized.